Telecommunications networks typically operate in accordance with a given standard or specification which sets out what the various elements of the network are permitted to do and how that should be achieved. For example, the standard or specification may define whether the user, or more precisely, user equipment or terminal is provided with circuit switched and/or packet switched service. The standard or specification may also define the communication protocols and/or parameters which shall be used for the connection. In other words, the standards and/or specifications define the “rules” on which the communication can be based on. Examples of the different standards and/or specifications for wireless communication include, without limiting to these, specifications such as GSM (Global System for Mobile communications) or various GSM based systems (such as GPRS: General Packet Radio Service), AMPS (American Mobile Phone System), DAMPS (Digital AMPS), WCDMA (Wideband Code Division Multiple Access) or TD/CDMA in UMTS (Time Division/Code Division Multiple Access in Universal Mobile Telecommunications System), IMT 2000 and so on.
In a typical wireless cellular communication system a base station serves mobile stations or similar terminal apparatus (mobile station MS in the GSM, User Equipment UE in the UMTS) via a wireless interface. Each of the cells of the cellular system can be served by an appropriate transceiver apparatus. For example, in the WCDMA radio access network the cell is served by Node B, which is connected to and controlled by an element called as a radio network controller (RNC) node. In the GSM radio network the cell is served by a base station (BTS), which is connected to and controlled by a base station controller (BSC) node. The BSC/RNC element may be connected to and controlled by a mobile switching center (MSC), a serving GPRS support node (SGSN) or similar facility. The controllers of a network are typically interconnected and there may be one or more gateways, such as a Gateway MSC (GMSC) or a Gateway GPRS support node (GGSN), for connecting the cellular network to other networks, such as to circuit or packet switched telephone or data networks, such as the Internet or an intranet. The gateway node provides one or several access points for the network to another network, that is a connection point between the two networks.
As mentioned above, the telecommunications network may be capable of providing wireless packet switched services. Examples of such networks include the GPRS (General Packet Radio Service) network, EDGE (enhanced data rate for GSM evolution) Mobile Data Network or an appropriate third generation telecommunication system such as the CDMA (code division multiple access) or TDMA (time division multiple access) based 3rd generation telecommunication systems that are sometimes referred to as Universal Mobile Telecommunication System (UMTS). All these relate to the transfer of data to and from mobile stations. For example, the GPRS standard is provided in conjunction with the GSM (Global System for Mobile communications) standard. The GSM standard is a circuit switched service and is originally designed for speech services. There are elements of the GSM standard and the GPRS standard which are in common. The GPRS networks are described in more detail e.g. in 3GPP Technical Specification 3G TS 23.060 version 3.2.0, “General Packet Radio Service (GPRS); Service description; Stage 2”, January 2000. This document is incorporated herein by reference. An adaptation of the GPRS standard is also being proposed for use with the third generation standard UMTS, which typically uses code division multiple access. The packet data part of the UMTS is contained in the above referenced 23.060 specification, i.e. 23.060 applies for packet switched data both for the UMTS and the GPRS.
The released GPRS and UMTS specifications specify four traffic classes (conversational, streaming, interactive and background) for the quality of service (QoS). The conversational class is indented for voice calls. The streaming class is indented for real-time traffic, such as for video-on-demand services. The interactive class may cover non-real time traffic with small delays, such as web browsing. The background class is for traffic that may tolerate greater delays, such as delays of 1 to 5 seconds.
The data may flow within each of the classes via different data flows i.e. data streams. For example, the current proposals for a QoS standard define the interactive traffic class and traffic handling priority parameters. In other words, the data traffic between different data flow paths in the interactive traffic class can be prioritised with another QoS parameter. This further QoS parameter will be referred to in the following as traffic handling priority.
When the end-user of a connection requests for data from a remote equipment (e.g. a server), the interactive class scheme may apply. The end-user may be a machine, a human and so on. Examples of the human interaction with the remote equipment include web browsing, data base retrieval, server access and so on. Examples of machines interaction with the remote equipment include polling for measurement records, automatic data base enquiries (tele-machines) and so on.
Interactive traffic is a data communication scheme that on an overall level may be characterised by the request-response pattern of the end-user. At the message destination there is an entity expecting the message (response) within a certain time period. Round trip delay time is therefore one important attribute of the scheme. Another characteristic feature of the interactive traffic is that the content of the data packets must be transparently transferred. The transfer should also occur with as low bit error rate as possible.
The traffic handling priority may be defined as a feature that specifies the relative importance for handling of all service data units (SDUs) belonging e.g. to a UMTS bearer compared to the SDUs of other bearers. The service data units (SDUs) may comprise a data packet or any other data transmission entity that may be seen as forming a unit.
The data units may be transferred via the network as a Packet Data Protocol (PDP) context. More particularly, PDP context refers to the part of the data connection that goes through the packet switched network (e.g. the GPRS/UMTS network). The PDP context can be seen as a logical connection from the wireless station to the access point of a gateway node, such as the GGSN, the access point being the connection point between the e.g. GPRS/UMTS mobile network and an external data network. The PDP context may also be referred to, instead of the term logical connection, as a logical association between the access point and the user.
The purpose of the priority feature within the interactive class is to be able to differentiate between the different bearer qualities. This is handled by using a traffic handling priority attribute, to allow the mobile network to schedule traffic accordingly. By definition, the priority is an alternative to absolute guarantees, and thus these two attribute types may not be used together for a single bearer.
The number of the PDP contexts is continuously changing. The inventors have found that this may make it difficult to keep the relative priorities of the PDP contexts in the interactive traffic class during the configuration thereof. The prior art known to the inventors does not recognise or address the problem. The current specifications or proposals for the standards do not specify any manner how to accomplish the actual treatment of the data packets that belong to the PDP contexts i.e. logical connections or associations in the interactive traffic class and may have different traffic handling priorities.
The handling of the data packets, however, may need to be addressed before implementing the system in order to provide fair treatment of individual data flows. A possibility would be to use a WFQ (weighted fair queuing) to address the problem. However, the simple use of WFQs might neglect the number of the logical connections using each traffic handling priority. This might also lead to unfair behaviour in a congestion situation e.g. such that a PDP context with a lower traffic handling priority has a possibility of receiving better service than a PDP context with higher traffic handling priority. In other words, a PDP context with a higher priority might experience lower throughput than a PDP context with a lower priority if the number of PDP contexts with the higher priority exceeds a critical value. In addition, a fair treatment of the logical connections PDP contexts based on the traffic handling priorities, or other similar parameters, may also be desired since in some applications the end users may be charged based on (entirely or partially) said parameters.